chemical bonding and molecular structure chapter 12 sec 12.8 - 12.10
TRANSCRIPT
Chemical Bondingand Molecular Structure
Chapter 12Sec 12.8 - 12.10
Goals:
1. To use Lewis Structures as a way to predict the geometry of Molecules
2. Determine if molecules are polar or nonpolar
VSEPR Model
• Valence Shell Electron Pair Repulsion Model
• Bonds (pairs of electrons) attempt to move as far away as possible from one another in a molecule
This explains the Geometry of H2O
Water is a “bent” molecule, because
of the lone pairs around the central
Oxygen atom
Various Geometry of Molecules
See Examples on Next Slides
(Hand-Out)
Polar or Non-polar Molecule?
A molecule may have polar covalent
bonds and not be polar overall
?????????
Geometry must also be considered
Ammonia (NH3) is polar
1. The bonds between hydrogen and nitrogen are polar covalent (∆EN = .87)
2. Pyramidal geometry of molecule points charges toward N
Carbon Dioxide is Non-polar
Even though the bonds between carbon and oxygen are polar covalent (∆EN = 1.0), the pull of electrons is in equal and opposite directions because CO2 is linear
Water is Wacky!
Water has some strange properties due to its structure